GridView multiple (hierarchical) header rows

Has anyone got any insight into how to get multiple (hierarchical) header rows for a WPF GridView implementation that retains the functionality of adjusting the columns widths by dragging the column dividers in the header row. Effectively the header rows
would be somewhat like a horizontal tree view bound to a hierarchical data object for the items source. I have seen (and tried to extend from it) a sample (http://www.designerwpf.com/2008/01/25/embedded-listview-columns-columns-within-columns/)
that gets 2 header rows but no more than that... I am trying to create a dynamic number of header rows where that number is driven by the number of levels in the hierarchical data object.